tcl: merge loops/tcl — complete Tcl 8.6 subset (329 tests)

Phases 1-6: Dodekalogue tokenizer/parser, eval engine, expr mini-language,
string/list/dict commands, proc + uplevel/upvar (the headline showcase),
catch/try/throw, namespaces + ensembles, generator coroutines, idiom corpus.

Resolved add/add conflicts by taking loops/tcl (the complete tested impl)
over the architecture branch's earlier prototype.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

plans/agent-briefings/tcl-loop.md

@@ -11,7 +11,7 @@ isolation: worktree
 
 ## Prompt
 
-You are the sole background agent working `/root/rose-ash/plans/tcl-on-sx.md`. Isolated worktree, forever, one commit per feature. Never push.
+You are the sole background agent working `/root/rose-ash/plans/tcl-on-sx.md`. Isolated worktree, forever, one commit per feature. Push to `origin/loops/tcl` after every commit.
 
 ## Restart baseline — check before iterating
 
@@ -42,7 +42,7 @@ Every iteration: implement → test → commit → tick `[ ]` → Progress log
 - **Shared-file issues** → plan's Blockers with minimal repro.
 - **Delimited continuations** are in `lib/callcc.sx` + `spec/evaluator.sx` Step 5. `sx_summarise` spec/evaluator.sx first — 2300+ lines.
 - **SX files:** `sx-tree` MCP tools ONLY. `sx_validate` after edits.
-- **Worktree:** commit locally. Never push. Never touch `main`.
+- **Worktree:** commit, then push to `origin/loops/tcl`. Never touch `main`.
 - **Commit granularity:** one feature per commit.
 - **Plan file:** update Progress log + tick boxes every commit.